Optical system and method for managing brightness contrasts between high brightness light sources and surrounding surfaces

ABSTRACT

An optical system and method provides at least one, and preferably an array of relatively small, high brightness light sources with a surrounding surface that exhibits brightness, thereby reducing the contrast between the high brightness produced by the light sources and the brightness of their surrounding surfaces. The optical system includes a light waveguide structure that captures a portion of the light from the individual high-brightness light sources, and then re-emits the source light to create brightness in the light sources&#39; surrounding surfaces. The optical system is particularly adapted for use with LEDs, but could be used with LEDS, but could be used with other high brightness light sources.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of application Ser. No. 12/397,22 filedMar. 3, 2009, pending, which claims the benefit of U.S. provisionalapplication No. 61/068,066 filed Mar. 3, 2008.

BACKGROUND OF INVENTION

The present invention generally relates luminaires and lighting systemsfor providing general and specialty lighting, and more particularly toluminaires and lighting systems employing light sources that arerelatively bright, such as light emitting diodes (LEDs).

LEDs are increasingly used in lighting applications because of theirenergy efficiency, that is, their ability to produce a given lumenoutput per watt consumed. Such light sources are relatively small andintensely bright. For example, an LED that is rated at just ⅛ watt andthat produces 30 lumens per watt can have a brightness of betweenapproximately 50,000 to 300,000 candelas per square meter for LED sizesranging from 25 mm² down to 4 mm². For LEDs having higher wattageratings the brightness increases dramatically.

Often LED are employed in applications where the intense brightness theyproduce contrasts with surrounding surfaces that are unilluminated orrelatively dark. Such brightness contrasts can produce visual discomfortand will, in many applications, be undesirable. The present inventionovercomes the problems associated with such contrasts in brightness byproviding a unique and versatile optical system and method for managingthe brightness of surfaces surrounding relatively bright light sourcesused by a luminaire or lighting system. The invention manages thebrightness contrast between bright light sources and surroundingsurfaces that are normally relatively dark without the need to addadditional sources of light to illuminate the surrounding surfaces. Anoptical system in accordance with the invention will also permit alighting designer to create different distributions of light from theoptical system.

SUMMARY OF THE INVENTION

The present invention involves an optical system and method forproviding at least one, and preferably an array of high brightness lightsources with a surrounding structure that captures and re-emits aportion of the light from the individual high-brightness light sources.The re-emitted light creates brightness in surfaces that surround thehigh brightness light sources and reduces observable brightnesscontrasts. The light source surround structure is provided in the formof one or more light waveguides in a plane (which could be flat orcurved) having at least one and preferably an array of source lightchannels into which or behind which high brightness light sources areplaced and through which a portion of the available light produced bythe high brightness light sources is emitted. Each of the source lightchannels present internal waveguide surfaces for capturing a portion ofthe light emitted by the light sources. The light waveguide orwaveguides that form the surround are provided with a light extractor,such as an optically bonded reflective diffuse surface, for extractingthe portion of the light captured by the waveguide through the frontfacing, light emitting surface of the waveguide that surrounds the lightsources. Because of this extracted light, the light emitting surfacewill exhibit a level of brightness that reduces brightness contrast withrespect to observable brightness produced by the light sources.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical depiction of a light waveguide illustrating thebasic light piping principle of such waveguides.

FIG. 2 is a graphical depiction of a light waveguide with an opticallybonded diffusing surface used for extracting light from the waveguide.

FIG. 3 is a partial sectional view of an optical system in accordancewith the invention, wherein an array of high-brightness light sourcesare set into a light waveguide for producing surround brightness thatreduces the contrast brightness between the surround surfaces and thelight sources.

FIG. 4 is an exploded perspective view of an optical system inaccordance with the invention as shown in FIG. 3, wherein the opticalsystem is configured in a square planar array of light sources.

FIG. 5A is a graphical depiction of a variation of an optical system inaccordance with the present invention, wherein the variation resides inthe size of the source light openings of the optical system's lightwaveguide.

FIG. 5B is a graphical depiction of another variation of an opticalsystem in accordance with the present invention, wherein the variationresides in the size of the source light openings of the optical system'slight waveguide.

FIG. 6 is a graphical depiction of a further variation of the lightwaveguide used in the optical system of the present invention, whereinthe variation resides in the thickness of the waveguide.

FIG. 7 is an exploded view of an LED post top luminaire employing anoptical system in accordance with the invention.

FIG. 8A is a bottom plan view thereof,

FIG. 8B is a cross-sectional view thereof taken along lines 8B-8B inFIG. 8A.

FIG. 9A is a graphical depiction of yet another variation of an opticalsystem in accordance with the present invention, wherein the variationresides in the placement of the light source in the source lightopenings of the light waveguide.

FIG. 9B is a bottom plan view of the optical system shown in FIG. 9A.

FIGS. 10 and 11 are graphical depictions of still further variations ofan optical system in accordance with the present invention, wherein thevariations reside in the shape of the light source light openings of thelight waveguide.

FIG. 12A is a graphical depiction of variation of an optical system inaccordance with the present invention, wherein the variation resides inthe edge treatment of the source light openings of the light waveguide.

FIG. 12B is a bottom plan view of the optical system shown in FIG. 12A.

FIG. 13 is a graphical depiction of an optical system in accordance withthe invention, wherein secondary optical control elements in the form ofprismatic lenses are provided at the front of the source light openingsin the light waveguide of the optical system.

FIG. 14 is a graphical depiction of an alternative version of thesecondary optical control elements shown in FIG. 13.

FIG. 15 is a graphical depiction of another alternative version of thesecondary optical control elements shown in FIG. 13.

FIGS. 16A-18 are graphical depictions of further alternative embodimentsof an optical system in accordance with the invention, wherein thesource light openings in the light waveguide are provided in the form ofstraight source light channels instead of round, oval or square openingsas illustrated in the foregoing figures.

FIGS. 19-21 are graphical depictions of yet further embodiments of anoptical system in accordance with the invention, wherein the sourcelight openings in the light waveguide are provided in the form of sourcelight channels that follow a curved path.

FIGS. 22-23 are graphical depictions of still a further alternativeembodiment of an optical system accordance with the invention, whereinthe source light openings in the light waveguide are provided in theform of straight source light channels formed by separate sections ofwaveguide.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present invention involves the management of the often extremebrightness contrasts that exist between small high brightness lightsources, such as LEDs, and surfaces that surround the light sources. Asused herein, the term “high brightness” means ranges of brightnesstypically produced by LEDs. While LEDs are referred to throughout thisdescription, it shall be understood that the invention is not limited tothe use of LEDs, but could employ other small commercially availablelight sources, such as plasma light sources, that exhibit similar levelsof brightness. The management of surround surface brightness is uniquelyachieved in the invention using light waveguides.

FIGS. 1 and 2 generally illustrate the principle of the light waveguideused in the invention. Light waveguides, also sometimes referred to as“light guides” or “light pipes,” are well known. The light waveguideworks on the principle of internal reflections governed by Snell's Law,and permits light introduced at the edges of the guide to be piped downthe guide without emerging from the guide's parallel surfaces. Referringto FIG. 1, a light waveguide 11 fabricated of a clear light transmittingmaterial, such as clear plastic or glass, has parallel top and bottomsurfaces 13, 15, and edges 17 through which light can be introduced intothe guide. In the illustrated waveguide, light is introduced into eachof the guide's edges 17 by means of graphically illustrated lightsources 19 a, 19 b. The light produced by these sources is piped downthe guide, as represented by light rays R1 with respect to light source19 a, and R2 with respect to light source 19 b. Because of the highangle of incidence of light rays R1 and R2 on surfaces 13, 15 of thewaveguide, the light rays will internally reflect off of these surfacesand consequently will not escape the guide. (The angle of incidence isthe angle at which the light ray strikes a surface relative to a lineperpendicular to the surface.)

Referring to FIG. 2, the extraction of the light produced by lightsources 19 a, 19 b can be achieved by providing an optical mechanism forchanging the manner in which the light rays reflect off one or the otherof the surfaces of the guide. In the case of the light guide shown inFIG. 2, the surface 13 of the guide is provided with a layer 21 of alight diffusing reflective material, which is optically bonded to thissurface. For example, the optically bonded surface can be provided inthe form of highly reflective diffuse paint, or a separate diffusereflector element bonded to surface 13 by an optical adhesive having areflective index that substantially matches the light waveguide. Theoptically bonded layer 21 acts as an “extractor” for the light piped infrom the edges 17 of the guide by changing the nature of the internalreflections from surface 13. The reflections are now diffuse in natureresulting in reflected light being scattered toward the opposite surface15 of the guide as represented by light rays R3. Scattered light thatstrikes the opposite surface 15 at low angles of incidence (closer tothe perpendicular) will emerge from this surface, which will cause thesurface to illuminate and exhibit brightness. The component of diffusedlight coming off surface 13 at high angles will continue to be pipeddown the waveguide for later extraction. Such techniques for extractinglight from a light waveguide are well known in the art.

FIG. 3 shows a lighting system in accordance with the invention whereinthe properties of a light waveguide are advantageously used to createsurround brightness around an array of LEDs (or other small bright lightsources) from a portion of the light emitted by the LEDs. Referring toFIG. 3, it can be seen that a light waveguide 25 is provided with anarray of source light openings 27 into which there is set an array ofLED light sources 29 mounted to a suitable back plate 30. Each of thesource light openings presents an internal light injection surface 31,which, in the illustrated embodiment, is perpendicular to the guide'sparallel front and back surfaces 35 and 36, but which could extendbetween the guide's front and back surfaces at an angle, or which couldbe an irregular surface designed to meet particular performancerequirements. (The singular “surface” as used hereinafter shall beunderstood to encompass internal surface configurations that have pluralsurfaces, such as four surfaces created by a square opening.) Theinternal light injection surfaces 31 of the source light openings 27receive a portion of the light emitted by the LEDs 29 as represented bylight rays R4, and this portion of the available light from the LEDs isinjected into and captured by the surrounding light waveguide. Anoptically bonded reflective diffuser layer 33 on the back surface 36 ofthe light waveguide provides an extractor for this captured light. Lightextraction is achieved by the diffusion or scattering of the lightreflected of the reflective diffuser layer as above-described and asrepresented by scatter light arrows R5. The scattered light emerges fromthe front surface 35 of the waveguide surrounding the LEDs, causingsurface 35 to exhibit brightness. To extract light, the reflectivediffuser layer 33 need not provide a perfectly diffuse surface, butcould provide a surface that is semi-diffuse, and reference herein to adiffuse layer or surface shall include a semi-diffuse layer or surfaceunless otherwise indicated.

As represented by light rays R6 in FIG. 3, much of the light, orluminous flux, that is produced by the LED light sources 29 emergesdirectly from the front light exit end 26 of the source light openings27. This directly emitted light will produce relatively intense visiblebrightness at each opening. However, the contrast normally producedbetween the source brightness and the surfaces that surround the lightsources is reduced by the fact that a portion of the source light iscaptured by the surrounding light waveguide and emitted through theguide's front surface 35. The degree of brightness produced on thissurrounding surface will depend on a number of factors including thepercentage of available source light captured by the light waveguide,the total light output of each LED, the density and distribution of theLEDs in the waveguide, the outer perimeter geometry of the waveguide,and the reflective properties of the reflecting diffuser layer backingof the waveguide.

In regards to the amount of available source light captured by thewaveguide, this could be changed by adjusting the degree of inset of theLED sources 29 within the source light openings 27 of waveguide 25. Aslater discussed, other techniques for adjusting the amount of lightcaptured by the waveguide can be employed, such as altering the shapeand/or size of the source light openings or the thickness of thewaveguide.

It will be understood that, rather than insetting the light sources intothe waveguide's source light openings as illustrated in FIG. 3, thelight sources could alternatively be positioned behind these opening inconjunction with secondary reflectors or other light control elementsthat direct light from the light sources into the openings. However,inset light sources are preferred because they provide greaterefficiency and would be easier to manufacture. It will also beunderstood that the shape of the LEDs illustrated in the drawings isillustrative only. LEDs having different shapes and that have shapedfront lenses incorporated into the LED could be used.

An implementation of the invention is further shown in FIG. 4, wherein asquare planar light waveguide 25 is provided with a 7×7 two-dimensionalarray of source light openings 27 for receiving a corresponding array ofLED light sources 29. The light sources of the array are mounted to arectangular back plate structure 30 and register with and are insetwithin the source light openings when the waveguide is secured to theback plate. It is contemplated that the back plate structure 30 can be aPC board on which the LEDs are mounted. The PC board can, in turn, bemounted to another structure that can act as a heat sink for the heatgenerated by the LEDs. The light waveguide can be secured to the backplate structure by any suitable means, such as by adhesive attachment ormechanical attachment, and supported by hardware and/or frame components(not shown). An optically bonded reflecting diffuser surface 36 providedon the back of the waveguide causes light that is injected into thewaveguide to be extracted through the waveguide's front surface 35. Toprevent the light that is injected into the waveguide from escapingthrough the waveguide's perimeter edges 38, the waveguide's perimeteredges can suitably be covered with a specular reflective material. Theinjected light from the LEDs will thus reflect off of the waveguideedges and continue to be piped through the waveguide until extracted.Extraction of the injected light through front face of the waveguidewill cause the front face of the waveguide to illuminate and exhibitbrightness, which will, in turn, cause a reduction in brightnesscontrast between the visible LEDs and their surrounding surfaces.

It will be appreciated that a planar array of light sources with awaveguide surround as described herein could be provided in a number ofshapes other than the square shape illustrated in FIG. 3, such as, forexample, a rectangular, hexagonal, circular, or donut shape. Thewaveguide surround could also be created using more than one waveguide.For example, multiple contiguous or non-contiguous waveguides could beused to create different surround waveguide shapes and configurationsfor capturing a portion of the light emitted by one or more highbrightness light sources. Also, the density of light sources within thearray of light sources could be non-uniform. That is, the spacingbetween the light sources and corresponding source light openings in thewaveguide could vary. The array could also be one-dimensional, as in aline of light sources.

Since, in a reasonably large array, light injected into the lightwaveguide will come from numerous dispersed light sources, it isanticipated that, with a continuous and uniform waveguide having uniformlight extraction characteristics, the amount of light extracted atdifferent regions within the waveguide surround will be relativelyconstant, resulting in relatively uniform brightness over the entirefront surface of the waveguide. It is anticipated this would be trueeven if the density of the light sources and corresponding source lightopens is non-uniform. However, if desired, the waveguide surround couldbe designed to produce non-uniform brightness across the front surfaceof the waveguide, such as by altering the light extractioncharacteristics of the waveguide in different regions of the guide.

Finally, it is noted that the waveguide surround shown in FIG. 4 couldlie in a curved plane or in a plane that has a combination of curves andflat areas. The light waveguide could further have front and backsurfaces that deviate somewhat from parallel, so long as there is enoughparallelism that light can be piped through the waveguide.

FIGS. 5A and 5B illustrate how the openings in the waveguide of theoptical system of the invention can be sized to control the cut-offangle of a luminaire, as well as the amount of source light injectedinto surrounding waveguide. (As used herein, the “cut-off” angle of aluminaire relates to a luminaire having an exposed light source andmeans the angle measured up from the nadir—straight down—to the firstline of sight at which the exposed light source is no longer visible.)In FIG. 5A, source light opening 41 of waveguide 43 is shown as having arelatively large diameter D1, such that the cutoff angle for lightproduced by the LED light source 45, as represented by light ray arrowsC1, is relatively high. This large diameter opening results in more ofthe available light from the LED being emitted from opening 41 and lessof the available light being injected into the waveguide through theinternal light injection surfaces 47 of the source light openings. Lesslight injected into the waveguide will also mean there will be lesslight extracted through the waveguide's light emitting front surface 49,and hence lower brightness for the waveguide surfaces surrounding theLED. (The higher cutoff angle will also mean that the LED will bevisible at higher viewing angles.)

In FIG. 5B, a waveguide 51 having the same thickness as the waveguideshown in FIG. 5A is provided with a source light opening 53 having asmaller diameter D2, wherein a greater portion of the available lightfrom the LED light source 55 is injected into the opening's internallight injection surfaces 57, as indicated by the lower cutoff anglerepresented by light ray arrows C2. As a consequence, more light will beextracted from the waveguide, resulting in surround surfaces for the LEDthat exhibit a higher brightness. Conversely, less of the availablelight will be emitted from the source light opening 53. The lower cutoffangle will also mean that the LED will not be visible at high viewingangles, which may be an advantage in many applications.

FIG. 6 illustrates how the amount of available light from the LED lightsource that is injected into the waveguide surround can be controlled byvarying the thickness of the light waveguide. As compared to the lightwaveguides shown in FIGS. 5A and 5B, the light waveguide 63 shown inFIG. 6 is relatively thick. Due to the extension of the internal lightinjection surfaces 65 of the guide's source light opening 67, a greateramount of available source light is injected into the waveguide, therebyincreasing the exhibited brightness of the waveguide surround. Thisextension of the guide's internal light injection surfaces is also seento lower the cutoff angle—represented by light ray arrows C3—for thesource light emitted from this opening. Thus, it can be seen that thebrightness of the light emitting surfaces of the light waveguidesurround of the optical system of the invention can be managed byvarying the depth and size of the source light openings in the lightwaveguide surrounding the high brightness light sources. Othercharacteristics of the source light openings could also be varied, suchas the shape of the openings.

FIGS. 7, 8A and 8B illustrate an example of an application for anoptical system in accordance with the invention. Shown is an LED posttop luminaire for illuminating outdoor public spaces. Luminaire 81,which is mounted to the top of post 83 by any suitable means ofattachment (not shown), is comprised of canopy housing 85, a lightwaveguide 89, an array LEDs 91, and an LED array driver 92 containedwithin the canopy housing. (The wiring of the LEDs and driver are notshown.) The bottom structure of the canopy housing is shown as having abottom wall 93 and a downwardly depending waveguide retaining skirt 95for holding the light waveguide 89, such that the bottom light emittingsurface 97 of the waveguide faces downward d the public space to beilluminated. The LED array is seen to be mounted to a back plate 96 thatcan be secured to the canopy housing bottom wall by any suitablesecuring means (not shown). Both the light waveguide 89 and back plate96 have suitable center openings 90, 94 for accommodating theluminaire's mounting post 83. It will be appreciated that the canopyhousing and its waveguide holding structure are illustrative only, andthat a wide variety housing structures for holding the LED array andlight waveguide are possible.

With further reference to the luminaire shown in FIGS. 7, 8A and 8B, thelight waveguide 89 of the luminaire is seen to include an array ofsource light openings 99 for receiving the array of LEDs 91. The LEDs,which are inset into these openings, supply light for the waveguide andfor general illumination. The light for general illumination is producedby light emitted from the bottom of the luminaire through the sourcelight openings 99. As discussed above, the light waveguide will have asuitable light extracting means, such as an optically bonded reflectivediffuse surface 101, for extracting the portion of the LEDs' light thatis injected into the waveguide through the waveguide's bottom lightemitting surface 97. The extraction of light through the guide's bottomsurface will produce brightness across the surfaces that surround theLEDs, thereby reducing the contrast in the brightness between theluminaires LEDs and its surrounding surfaces.

FIGS. 9A and 9B illustrate a variation of the invention, wherein thebright light sources of the waveguide optical system are positioned toalter the light intensity distribution of the source light that isemitted from the waveguide's source light openings. Rather than beingcentered within the source light openings, in FIGS. 9A and 9B, the lightsources, such as LEDs 105, are seen to be offset within the circularopenings 107 of light waveguide 109. By offsetting the light sourceswithin the waveguide openings, the cutoff angles around the openings canbe manipulated, as graphically illustrated by the light ray arrows C_(h)and C_(L), where C_(h), represents a high cutoff angle and C_(L)represents a low cutoff angle. In such a configuration, a luminaire suchas shown in FIGS. 7, 8A, and 8B, could be created where high brightnessproduced by the bright light sources could be suppressed at high angleswhen viewed from one direction, while a wider distribution of lightresulting from a higher cutoff angle is achieved in the other direction.It is seen that the light emitting surface 111 of the light waveguide109 will produce a surround brightness for the offset light sources 105.(Where the surround brightness produced across the waveguide's lightemitting surface is produced from the cumulative effect light injectedinto the guide from multiple sources, it is contemplated that theoffsetting of the light sources in the guide openings will notappreciably affect the uniformity of the brightness across the lightwaveguide.)

FIGS. 10 and 11 show examples of light waveguides in accordance with theinvention, wherein the waveguide source light openings are provided indifferent shapes for achieving different desired lighting effects. FIG.10 shows light source openings 115 having an oval shape with the lightsources 117 offset within the oval openings; FIG. 11 showsrectangular-shaped openings 121 with light sources 123 similarly offset.It will be appreciated that the light sources 117, 123 shown in FIGS. 10and 11 could be centered within the shown out-of-round light sourceopenings.

FIGS. 12A and 12B show yet another variation of the configuration of thesource light openings of the light waveguide used in the optical systemof the invention. In FIGS. 12A and 12B, the light waveguide 125 isprovided with source light openings 127, wherein the front edge 129 ofthe opening 127 is modified to alter the cutoff angle of the lightemitted through the openings by the bright light sources 131. In thesefigures, a chamfer 133 is provided along one side of the opening toproduce a high cutoff angle C_(h) on the chamfered side and a lowercutoff angle on the non-chamfered side. However, it will he understoodthat a symmetric or an asymmetric chamfer could be provided around theentire opening so as to raise the cutoff angle around all sides of thewaveguide.

It is noted that different configurations for the source light openingsin the waveguide of the lighting system of the invention can be combinedwithin a single lighting system. Thus, for example, it is within thescope of the invention to provide a waveguide with a mixture ofcircular, oval and/or square source light openings, and to provide someof the openings with chamfered edges and some without.

FIGS. 13-15 illustrate how secondary optical control elements, such asprismatic lenses, can be used in connection with the waveguide of theinvention for creating a desired light distribution from the sourcelight exiting the waveguide's source light openings. In FIG. 13, atransparent secondary lens plate 137 is placed in front of the lightwaveguide 139 over the source light openings 141 in the light waveguide.The lens plate 137 is provided with prismatic lens portions, which inthe illustrated embodiment are prismatic surfaces 145 formed on thefront surface 147 of the lens plate. It is seen that the prismatic lensportions are located on the lens plate so that they register with thesource light openings. Thusly located, light emitted by the LEDs that isnot injected into the surrounding waveguide will pass through and becontrolled by the prismatic lenses.

FIG. 14 shows an embodiment of the invention similar to that shown inFIG. 13, except that instead of providing a lens plate that covers thebottom of the light waveguide 139, separate lens element inserts 149 areplaced in the front light exiting end of the source light openings ofthe light waveguide.

FIG. 15 shows an embodiment in which the lens elements are integratedinto the light waveguide. In this embodiment, source light openings 151,which receive light from LEDs 143, are provided in the back 153 of thelight waveguide 155 to a suitable depth that leaves a transparent wall157 at the bottom of the source light openings. Prismatic surfaces 159are provided on the front of the transparent wall 157 at the front lightexisting end of the openings.

It is noted that the range of optical control elements that can be usedto control light emerging from the front light exiting end of the sourcelight openings of the waveguide is not limited to the prismatic lensesillustrated in FIGS. 13-15. Also, the prismatic lenses need not coverthe entire source light opening as illustrated, but could cover only aportion of the opening. Further, a prismatic surface could be providedon interior surfaces as well as exterior surfaces of the lens elements.

It is seen that, unlike in previously described embodiments, in theembodiments of the invention illustrated in FIGS. 13-15, the LEDs wouldnot be directly visible to the observer at any viewing angle. Usingsecondary optics that cover the light sources, the contrast inbrightness on the observable surfaces of the luminaire would be producedby a contrast between the brightness of the observable optical elementsin front of the light sources and the brightness produced in thewaveguide surfaces surrounding the light waveguide. In addition toproviding greater control over light intensity distribution, secondaryoptical control elements can be designed to control brightness at thefront of the source light openings. Thus, their use at the front of thesource light openings would provide the lighting designer with an addedtool to manage contrast brightness.

FIGS. 16 -22 show yet further alternative embodiments of the inventionwherein source light openings are provided in the light waveguide in theform of elongated channel openings. These channel openings could becurved or straight and can be distributed in different patterns in thewaveguide. At least one high brightness light source, and most suitablya string of LEDs are arranged in or in relation to the channel openingsso that a portion of the light emitted by a light source or sources isinjected into and then extracted from the front observable surface ofthe waveguide as above-described.

Referring to FIGS. 16A, 16B and 17, a luminaire light waveguide 201 heldin a frame 203 has a front surface 205 and a back surface 207, and isseen to have light source openings in the form of a series of straightsource light channels 209, each of which provide internal lightinjection surfaces 211 that are perpendicular to the waveguide's frontand back surfaces 205, 207. A series of high brightness light sources isset in each of light channels for producing source light along thelength of the channels. The light sources are suitably a string of LEDs213 spaced equidistant apart over substantially the length of eachchannel. And this string of LEDs is suitably mounted to a back plate 214which covers the back surface of the waveguide. It is noted that theends 209 a of the source channels 209 are set back from the edges 202 ofthe light waveguide such that the waveguide completely surrounds each ofthe channels. In this configuration, light can be injected into thewaveguide along the long light injection surfaces 211 a and therelatively short end light injection surfaces 211 b. As will beillustrated in further examples described below, source light channelscan be provided in the light waveguide in a wide variety of channelconfigurations, including configurations where the light waveguide onlypartially surrounds the channels, or continuous channels with continuouslight injection surfaces and no channel ends.

With further reference to FIGS. 16A, 16B and 17, it is seen that eachsource light channel 209 is seen to provide internal light injectionsurfaces 211 in the waveguide which receive a portion of the lightemitted by the LED string set in the channel. This portion of theavailable source light, which is represented by light rays R4, isinjected into and captured by the surrounding light waveguide. Thisinjected portion of source light is extracted through the front surfaceof the waveguide by optically bonded reflective diffuser layer 215 onthe waveguide's back surface 207. As described above, the extractedlight emerges from the front surface 205 of the waveguide whichsurrounds the LED channels, causing the waveguide's front surface 205 toexhibit brightness. Again, it is noted that the reflecting diffuserlayer 215 need not provide a perfectly diffuse surface, but couldprovide a semi-diffuse surface.

As represented by light rays R6 in FIG. 16B, much of the light, orluminous flux, that is produced by the LED strings 213 is not injectedinto the light waveguide, but rather travels forwardly so as to emergedirectly from the front light exit end 210 of the source light channels209. This directly emitted light will produce relatively intense visiblebrightness along each channel for illuminating the space in front of thewaveguide.

FIG. 16C shows a variation of the light waveguide illustrated in FIGS.16A and 16B. Here, the light waveguide 217 has elongated parallel sourcelight channels 219, which do not extend through the entire thickness ofthe waveguide as in the previously described embodiment, but ratherpartially into the waveguide to a depth that leaves a channel back wall220 against which the series of LEDs 213 can be mounted. Like thepreviously described version, a reflecting diffuser layer 221 can beapplied to the back surface 223 of the waveguide to achieve lightextraction through the guide's front surface 225. The partial depthchannels can be routed channels or formed by other manufacturing means.

FIG. 18 shows an alternative embodiment of the light waveguide wherein,instead of straight source light channels that are completely surroundedby the light waveguide, the light waveguide only partially surrounds thechannels. Here, light waveguide 227 has a series of straight sourcelight channels 229 shifted to opposite edges 228 of the waveguide toform interleaved channels, each of which has one of its ends 229 afacing the waveguide frame 226. As in the previous embodiment, eachshifted channel provides light injection surfaces 230, which includeslong light injection surfaces 211 a and a short end light injectionsurface 230 a. Source light would not be injected into the waveguide atchannel end 229 a which faces waveguide frame 226. Light sources such asa string of LEDs are inset into the channels which are open to the frontof the waveguide. As with the previously described embodiments, aportion of the light emitted by these light sources is injected into andthen extracted from the front of the waveguide. The portion not injectedinto the light waveguide emerges directly from the front light exit endof the source light channels without being injected into the waveguide.This portion of the emitted light illuminates the space in front of thewaveguide.

In the embodiment shown in FIGS. 19-20, light waveguide 231 has a singlegenerally circular, or more precisely oval, source light channel 233instead of straight channels. Light sources, such as the shown string ofLEDs 231, are inset in this channel such that a portion of the lightemitted by the light sources is injected into the channel's opposedcurved light injection surfaces 234. The portion not injected intowaveguide 231 emerges from the front of the guide to illuminate a space.FIG. 21 shows another example of the use of curved channels. Here,waveguide 235 is provided with half circle channels 237 which providecurved light injection surfaces 238. A string of LED light sources 231can be inset into each of these channels as shown.

In the embodiments shown in FIGS. 19-21, a partial depth channel ispreferably used an that the waveguide can be fabricated from a singlesheet of transparent material. The waveguide surrounds the source lightchannel in that it borders both the inner and outer sides of the ovalring that constitutes the channel. It will be appreciated that manydifferent configurations of source light channels are possible thatfollow curved paths, such as S-configurations, and that source lightchannels with different curved configurations or curved and straightconfigurations could be combined in a single light waveguide.

FIGS. 22-23 illustrate an example wherein the light waveguide, denoted bthe numeral 250, can be fabricated in sections, in this case a topsection 239, a middle section 241 and a bottom section 243, all of whichare mounted to back plate 249 so as to form two source light channels245, 247. Source light channels 245, 247 present opposed internal lightinjection surfaces 240, 242 which extend the width of the waveguide andthough which a portion of the light emitted by light sources 213 can beinjected into the waveguide sections. The back of each waveguide section239, 241, 243, such as back surface 251 of section 239, can be providedwith a reflecting diffuser layer (not shown) for light extraction. Aswith the earlier described embodiments, a substantial portion of thelight emitted by the light sources 213 emerges from the front of thesource light channels 245, 247 without being injected into the waveguidesection. As before, this portion of the emitted light is used toilluminate a space.

It will be appreciated that secondary optical control elements, such asprismatic lenses, can be placed in or over the front openings of thesource light channels in the embodiments of the invention illustrated inFIGS. 16A-23 in a manner similar to the lens elements illustrated inFIGS. 13-15 for controlling the distribution of light from the waveguideor brightness at these openings. The optical elements can be elongatedoptical elements that cover the front opening of the source lightchannel or channels over the entire length of the channel or channels,or only a portion of the channel length. Where there is more than onesource light channel, optical elements can be placed in or over all orless than all of the channels.

While the invention has been described in considerable detail in theforegoing specification, it will be understood that it is not intendedthat the invention be limited to such detail, or to the variousembodiments disclosed herein, unless such limitations are expresslyindicated or recited in the following claims. Variations of theinvention not expressly disclosed herein, but which fall within thespirit and scope of the invention, will be evident to persons ofordinary skill in the art.

What I claim is:
 1. An optical system for managing the brightness ofsurfaces surrounding one or more high brightness light sources of aluminaire or lighting system for providing illumination within a space,comprising a substantially planar light waveguide having a front with anobservable front surface and a back with a back surface, at least onesource light opening in said light waveguide, wherein said light sourceopening is in the form of a channel, wherein at least a portion of theobservable front surface of said light waveguide at least partiallysurrounds the channel forming said source light opening, and wherein theportion of the observable front surface surrounding said source lightopening is light transmissive, the channel which forms said source lightopening providing internal light injection surfaces in said waveguide,and at least one high brightness light source for producing source lightfor the luminaire, said high brightness light source being positioned inrelation to the back of the light waveguide and the channel forming thesource light opening therein such that the following conditions are met:a) source light is emitted from said high brightness light source over asubstantial portion of the channel forming the source light opening, b)a portion of the available source light emitted by said light sourcetravels forwardly of said light source and exits the front of the lightwaveguide without being injected into the waveguide so as to produce anobservable area of high brightness at the front of the light waveguide,said area of source brightness providing illumination within a space,and c) a portion of the available source light from said light source isinjected into the light waveguide through the internal light injectionsurfaces provided by the channel forming the source light opening insaid light waveguide, said light waveguide having means for extractingsource light that is injected into said light waveguide through at leastthe portion of the front surface of the waveguide that at leastpartially surrounds the channel forming said source light opening,wherein at least the portion of the front surface of said lightwaveguide that at least partially surrounds the channel forming saidsource light opening exhibits elevated brightness that mitigates theobservable contrast in brightness between the area of high brightnessproduced by the high brightness light source and the front surface ofthe light waveguide that at least partially surrounds the source lightchannel.
 2. The optical system of claim 1 wherein said at least onelight source is at least partially inset into the channel forming the atleast one source light opening of said light waveguide.
 3. The opticalsystem of claim 1, wherein a plurality of light sources are positionedin relation to the back of the light waveguide and the channel formingthe source light opening such that the light sources are distributedalong said channel.
 5. The optical system of claim 1 wherein the sourcelight opening in said light waveguide is comprised of at least onestraight elongated channel.
 6. The optical system of claim 1 wherein aplurality of source light openings are provided in said light waveguidein the form of a plurality of straight elongated channels.
 7. Theoptical system of claim 6 wherein said light waveguide has edges and atleast one of said plurality of straight elongated channels extends to anedge of the light waveguide.
 8. The optical system of claim 1 whereinthe channel forming said source light opening follows a curved path. 9.The optical system of claim 8 wherein the channel forming said sourcelight opening is comprised of at least one generally circular channel.10. The optical system of claim 8 wherein the channel forming saidsource light opening is comprised of at least one generallysemi-circular channel having ends.
 11. The optical system of claim 10wherein said light waveguide has edges and the ends of said generallysemi-circular channel extend to an edge of the light waveguide.
 12. Theoptical system of claim 1 wherein said means for extracting injectedsource light through the front surface of said light waveguide includesa reflective diffuse layer optically bonded to the back surface of saidlight waveguide.
 13. An optical system for managing the brightness ofsurfaces surrounding one or more high brightness light sources of aluminaire or lighting system for providing illumination within a space,comprising a substantially planar light waveguide having a front with anobservable front surface and a back with a back surface, at least onesource light channel in said light waveguide, wherein at least a portionof the observable front surface of said light waveguide at leastpartially surrounds said source light channel, wherein the portion ofthe observable front surface surrounding said source light channel islight transmissive, and wherein said source light channel providesinternal light injection surfaces in the waveguide, and a plurality ofhigh brightness light sources for producing source light for theluminaire, said high brightness light sources being distributed over asubstantial portion of said source light channel such that the followingconditions are met: a) source light is emitted from said high brightnesslight sources over a substantial portion of said source light channel,b) a portion of the available source light emitted by said light sourcestravels forwardly of said light sources and exits the front of the lightwaveguide without being injected into the waveguide so as to produce anobservable area of high brightness at the front of the light waveguide,said area of source brightness providing illumination within a space,and c) a portion of the available source light from said light sourcesis injected into the light waveguide through the internal lightinjection surfaces provided by the source light channel, said lightwaveguide having means for extracting source light that is injected intosaid light waveguide through at least the portion of the front surfaceof the waveguide that at least partially surrounds said source lightchannel, wherein at least the portion of the front surface of said lightwaveguide that at least partially surrounds the source light channelexhibits elevated brightness that mitigates the observable contrast inbrightness between the area of high brightness produced by the highbrightness light sources and the front surface of the light waveguidethat at least partially surrounds the source light channel.
 14. Theoptical system of claim 13 wherein the source light channel in saidlight waveguide is comprised of at least one straight elongated channel.15. The optical system of claim 13 wherein the source light channel insaid light waveguide follows a curved path.
 16. The optical system ofclaim 13 wherein a plurality of source light channels are provided insaid light waveguide, each of said source light channels having aplurality of high brightness light sources distributed over asubstantial portion of the source light channel.
 17. The optical systemof claim 13 wherein said light waveguide has edges and at least onesource light channel extends to one of the edges of the light waveguide.18. The optical system of claim 13 wherein said means for extractinginjected source light through the front surface of said light waveguideincludes a reflective diffuse layer optically bonded to the back surfaceof said light waveguide.
 19. The optical system of claim 13 wherein saidlight waveguide is provided in separate sections with at least onesource light channel being formed between sections of waveguide.